A chap on our site told me the only way to grow swedes is with friends! Therefore, he sows his with the rest of his brassicas, closely! I am trying, but once again, it is looking like mine have failed.
Turnips on the other hand have done really well. Watch the flea beetles as they will decimate the leaves early on and the plants may not recover. I used one light dusting of derris, and they have thrived since then. Mine were called snowball. :)